Luminescent crystals and manufacturing thereof

Abstract

The present invention relates to the field of luminescent crystals (LCs), and more specifically to Quantum Dots (QDs) of formula M 1 a M 2 b X c , wherein the substituents are as defined in the specification. The invention provides methods of manufacturing such luminescent crystals, particularly by dispersing suitable starting materials in the presence of a liquid and by the aid of milling balls; to compositions comprising luminescent crystals and to electronic devices, decorative coatings; and to intermediates comprising luminescent crystals.

The invention claimed is: 
     
       1. A composition in the form of a suspension comprising:
 (i) luminescent crystals of 2-50 nm size of formula I):
   M 1   a M 2   b X c   (I),
 
 
 wherein
 M 1  represents one or more alkaline metals selected from Cs, Rb, K, Na, and Li, 
 M 2  represents one or more metals selected from the group consisting of Ge, Sn, Pb, Sb, and Bi, 
 X represents one or more anions selected from the group consisting of Cl, Br, and I, 
 a represents 1-4, 
 b represents 1-2, 
 c represents 3-9; 
 
 and 
 (ii) surfactant selected from the group of non-ionic, anionic, cationic and zwitterionic surfactants; and 
 (iii) optionally solvent, said solvent selected from the group of aliphatic hydrocarbons, esters, alcohols, and ketones; and 
 (iv) at least one acrylate polymer or at least one acrylate pre-polymer. 
 
     
     
       2. The composition according to  claim 1 , wherein
 the weight ratio luminescent crystals (i):liquid material (ii)+(iii)+(iv) is in the range of 0.0001-0.5; and/or 
 the weight ratio surfactant (ii):luminescent crystals (i) is in the range of 100-0.05; and/or 
 wherein the polymer or pre-polymer concentration is in the range of 0.1-30 wt %, of the total composition. 
 
     
     
       3. A composition according to  claim 1 , wherein said surfactants comprise apolar end-groups selected from the group of alkyl or alkyl-ether chains with 4-30 carbon atoms. 
     
     
       4. A composition according to  claim 1 ,
 which is free of solvents (iii), and 
 wherein the weight ratio luminescent crystals (i):liquid material (pre-polymer (iv)+surfactant (ii)) is in the range of 0.0001-0.5. 
 
     
     
       5. A composition according to  claim 1 , wherein the at least one polymer or pre-polymer (iv) comprises at least one acrylate pre-polymer. 
     
     
       6. A solid polymer composition comprising:
 (ii) luminescent crystals of 2-50 nm size of formula (I):
   M 1   a M 2   b X c   (I),
 
 
 wherein:
 M 1  represents one or more alkaline metals selected from Cs, Rb, K, Na, and Li, 
 M 2  represents one or more metals selected from the group consisting of Ge, Sn, Pb, Sb, and Bi, 
 X represents one or more halogenides selected from the group consisting of Cl, Br, and I, 
 a represents 1-4, 
 b represents 1-2, 
 c represents 3-9; 
 
 and 
 (iii) surfactant selected from the group of non-ionic, anionic, cationic and zwitterionic surfactants; and 
 (iv) a hardened/cured polymer, wherein the polymer comprises at least one acrylate. 
 
     
     
       7. The solid polymer composition according to  claim 6 , wherein
 the weight ratio of said luminescent crystals matrix (polymer+surfactant) is in the range of 0.0001-0.1; or 
 the weight ratio of said surfactant:luminescent crystals is in the range of 100-0.05. 
 
     
     
       8. The solid polymer composition of  claim 6 , wherein the surfactant comprises a zwitterionic surfactant. 
     
     
       9. A composition according to  claim 6  for converting blue light into white light. 
     
     
       10. A composition according to  claim 6  for converting blue light into white light in a light emitting diode (LED) or in a liquid crystal display. 
     
     
       11. An intermediate good comprising a sheet-like substrate coated with one or more layers, wherein at least one of said layers is a functional layer, wherein said functional layer comprises a composition according to  claim 6 . 
     
     
       12. An intermediate good according to  claim 11 , wherein said functional layer converts blue light into white light. 
     
     
       13. A device, selected from the group of electronic devices and optical devices, wherein said device comprises a substrate and a functional layer; and wherein said functional layer comprises luminescent crystals of formula (I):
   (I): 
   M 1   a M 2   b X c   (I),
 
 wherein:
 M 1  represents one or more alkaline metals selected from Cs, Rb, K, Na, and Li, 
 M 2  represents one or more metals selected from the group consisting of Ge, Sn, Pb, Sb, and Bi, 
 X represents one or more halogenides selected from the group consisting of CL, Br, and I, 
 a represents 1-4, 
 b represents 1-2, 
 c represents 3-9; 
 
 surfactant selected from the group of non-ionic, anionic, cationic and zwitterionic surfactants; and 
 at least one polymer, said at least one polymer comprising an acrylate. 
 
     
     
       14. The device according to  claim 13 , selected from the group consisting of displays, mobile devices, light emitting devices, and solar cells. 
     
     
       15. A device according to  claim 13 , selected from the group consisting of LCD displays or a quantum dot LEDs. 
     
     
       16. An article comprising a substrate and a coating, said coating comprising luminescent crystals of formula
   M 1   a M 2   b X c   (I),
 
 wherein:
 M 1  represents one or more alkaline metals selected from Cs, Rb, K, Na, and Li, 
 M 2  represents one or more metals selected from the group consisting of Ge, Sn, Pb, Sb, and Bi, 
 X represents one or more halogenides selected from the group consisting of Cl, Br, and I, 
 a represents 1-4, 
 b represents 1-2, 
 c represents 3-9; 
 
 surfactant selected from the group of non-ionic, anionic, cationic and zwitterionic surfactants; and 
 at least one polymer, said at least one polymer comprising an acrylate. 
 
     
     
       17. A method for manufacturing an intermediate good comprising a sheet-like substrate coated with one or more layers, wherein at least one of the layers is a functional layer, the method comprising the steps of:
 (a) providing a substrate, and 
 (b) forming a solid polymer according to  claim 6  to said substrate by applying a suspension comprising the luminescent crystals, the surfactant and at least one acrylate polymer or at least one acrylate pre-polymer, followed by drying and/or curing, said solid polymer composition being said functional layer.